Before I make my statement, I am sure that the House will want to join me in sending condolences to the family and friends of the sapper from 32 Engineer Regiment who sadly died while on duty in Helmand province yesterday as a result of non-battle related injuries sustained in Camp Bastion. The incident is not believed to have involved any enemy action. The serviceman’s next of kin have been informed and have requested the customary 24-hour delay before further details are released.

With permission, Mr Speaker, I wish to inform the House that I have decided to refuel the nuclear reactor in HMS Vanguard, one of the UK’s four ballistic missile submarines, during its planned deep maintenance period, which begins in 2015. It will be the second time that Vanguard’s reactor has been refuelled since it entered service in 1993. I will explain to the House now why I have reached the decision to conduct a second refuelling.

As many hon. Members will know, alongside the operational reactors on board our ballistic missile submarines, a prototype reactor of the same class has been running at the naval reactor test establishment at Dounreay in Scotland since 2002. Its purpose is to help us assess how the reactor cores within our submarines will perform over time. It has therefore been run for significantly longer periods and at a significantly higher intensity than the cores of the same type in our submarines, to allow us to identify early any age or use-related issues that may arise later in the lives of the operational reactor cores.

In January 2012, low levels of radioactivity were detected in the cooling water surrounding the prototype core. Low levels of radioactivity are a normal product of the nuclear reaction that takes place within the fuel, but they would not normally enter the cooling water. The water is contained within the sealed reactor circuit, and I can reassure the House that there has been no detectable radiation leak from that sealed circuit. The independent Defence Nuclear Safety Regulator and the Scottish Environment Protection Agency have been kept informed.

When the coolant radioactivity was first detected, the reactor was shut down as a precaution. Following investigations and a series of trials, and with the agreement of the relevant regulator, the reactor was restarted in November 2012. It continues to operate safely. Both radiation exposure for workers at the site and discharges from the site have remained well inside the strictly prescribed limits set by the regulators. Indeed, against the International Atomic Energy Agency’s measurement scale for nuclear-related events, this issue is classed as level , which is described by the agency as

“below scale—no safety significance”.

The naval reactor test establishment is, and remains, a very safe and low-risk site. However, the fact that low levels of radioactivity have been detected in the coolant water clearly means that the reactor is not operating exactly as planned. As one would expect, we have conducted extensive investigations to determine how the radioactivity has entered the cooling water. We believe that it is due to a microscopic breach in a small area of the metal cladding that surrounds one fuel element within the core of the reactor. It is not yet clear why that breach has occurred. It might be related to the age of the reactor, it might be a function of the high intensity use to which we have subjected the test reactor or it might be a random event. We do not yet know.

On current plans, the Dounreay test reactor will start to be decommissioned in 2015. We are confident that the reactor can be operated safely until that date. We may decide to bring forward decommissioning if it will allow us better to understand the causes of the breach through examination of the reactor core.

This occurrence does not present any safety risk. It does, however, potentially present additional risks to future submarine availability. Consequently, I have had to consider carefully the implications for the Vanguard-class and Astute-class submarines, which use the same design of reactor core. We constantly monitor our submarine reactors. We have never detected a similar occurrence to that found in the prototype reactor. We are confident that if one did occur, we would detect it straight away.

Despite that, we now have to consider the possibility, however remote, that the useful operating life of this particular design of core may not be as long as previously expected. As a result, I have decided that, as a precautionary measure, we should refuel HMS Vanguard, the oldest SSBN and the one with the highest mileage, as it were, on her reactor, when she enters her scheduled deep maintenance period in 2015. This is the responsible option: replacing the core on a precautionary basis at the next arising opportunity, rather than waiting to see if the core needs to be replaced at a later date, which would mean returning Vanguard for a period of unscheduled deep maintenance, potentially putting at risk the resilience of our ballistic missile submarine operations.

The refuelling will increase our confidence that Vanguard will be able to operate effectively and safely until the planned fleet of Successor submarines begins to be delivered from 2028. The refuelling will be conducted within the current planned dry dock maintenance period for Vanguard, which starts in late 2015 and will last for about three and a half years. It is therefore expected to have no impact on deterrent operations. The additional cost of refuelling Vanguard is estimated to be about £120 million over the next six years.

A decision on whether to refuel the next oldest submarine, HMS Victorious, when she enters her next planned deep maintenance period does not need to be made until 2018. It will be informed by further analysis of the data from the reactor at Dounreay and examination of the core after the reactor is decommissioned. I have decided, again on a precautionary basis, that in the meantime we will take the necessary steps to keep open the option of refuelling Victorious. That will involve investment at Devonport and at the reactor plant at Raynesway in Derby to preserve our ability to conduct nuclear refuelling. The total cost of that investment is still being scoped, but it is expected to be of the order of £150 million.

Those costs—perhaps £270 million in total—will be met from existing provision for financial risk in the submarine programme budget. They represent substantially less than 10% of that risk provision and will not impact on the more than £4 billion of contingency that we are holding in the overall defence equipment plan.

The implications for the Astute-class submarines will be the subject of further analysis, particularly once we have had the opportunity to examine the core from Dounreay. As the Astutes are only now entering service, and thus their cores have seen far less operation, a decision on whether to refuel any of them will not be needed for many years to come. These decisions do not affect our plans for the Successor submarine that will replace the Vanguard class. Refuelling HMS Vanguard does not enable us to further extend the overall life of the submarine, which is limited by a number of factors other than the age of the reactor. Neither do these decisions have any implications for our confidence in the reactor we are developing for the Successor submarine, which is based on a completely different design.

Finally, the House will understand that our naval reactor cores are a highly specialised, UK-bespoke maritime design, and there is no read across from this occurrence to the performance of naval reactors operated by other countries, or indeed reactors operating in the UK civil nuclear sector. The safety of the UK’s naval nuclear reactor at the test establishment at Dounreay, and on our submarines, is of critical importance to us, as is the maintenance of continuous at-sea deterrence. That is why I have taken the decision to apply the precautionary principle, even though there is no evidence at this stage that the problem detected with the test reactor is likely to present in the operational reactors. We will continue to work with independent military and civil regulators to ensure the continuing safety of nuclear operations at Dounreay, Devonport, Faslane and at sea.

The Government are committed to maintaining our nuclear deterrent as the ultimate guarantee of the UK’s sovereignty and freedom of action against threats of nuclear aggression, wherever they may come from. Our submarine-based continuous at-sea deterrent remains the most capable and cost-effective way of doing that. The decisions I have announced today are responsible and precautionary, and will assure our ability safely to maintain the UK’s nuclear deterrent into the future. I commend this statement to the House.

I join the Defence Secretary in paying tribute to the soldier from the 32 Engineer Regiment. His death is a reminder of the service and sacrifice given to our country by the armed forces, and our thoughts are with his family and loved ones at this time. I thank the Secretary of State for briefing me on this statement last night, and for sight of it. These are complicated and sensitive matters, and it is in all our interests that they are debated in a calm and reasonable manner that befits the seriousness of the issue.

I will come to the specific issues raised about the reactor in Dounreay and the nuclear submarines, but I start by asking the Secretary of State why he is making this statement now, and why the House is being told about this matter only today. He says that this issue was discovered in January 2012, which is more than two years ago. Does he not think it would have been right to brief the official Opposition spokesperson on defence then? Why did that not happen, and why has it not happened at any time since then until now? Should Parliament have known earlier?

There must be public confidence in the Government to be open and transparent about such matters. A fault, however small, that develops in a nuclear reactor is something that the British people, and this Parliament, should have been told about. This is an issue of national security and national importance, and it will cause particular concern in Scotland. When did the Scottish Secretary know? Did the Defence Secretary or his right hon. Friend the Secretary of State for Scotland discuss the issue with the First Minister of Scotland and the Scottish Government? It seems to me that it was incumbent on the UK Government to inform and work with the Scottish Government on this matter. I accept that the Secretary of State briefed me and other colleagues last night and this morning, and I appreciate his candour, but does he agree that it has come rather late?

Let me turn to the specific issues with the PWR2 nuclear reactor at Dounreay and the implications for the Royal Navy’s fleet submarines and ballistic missile submarines. There will inevitably be concern when the words “nuclear”, “reactor” and “fault” are used in the same sentence. Can the Secretary of State provide further assurance that there has been, and there is now, absolutely no risk to workers on site, personnel in service, or the wider public? Having discovered that there was a problem at the Vulcan naval reactor test establishment, on what basis was the decision made to continue running the reactor? We know it is now in maintenance. Will he tell the House when a decision will be made about whether to continue running the reactor? I understand that if a decision is made to stop running it, it takes three years from the point at which it shuts down to the point at which it has cooled enough to be examined. That is a long time. Has he examined the potential to look at the PWR2 currently being constructed for the later Astute-class boats, and does that provide an opportunity effectively to X-ray every aspect of the cladding to see if we can detect any faults? There will be concerns about the impact that might have on the Astute-class submarines. Will the Secretary of State outline what those are?

The decision to maintain a test reactor so that faults could be identified has proven a good one. A fault has been found, however small, in PWR2—the test reactor in Dounreay. What plans are there to ensure that we have the same security with PWR3, which will be used on the Successor-class submarines? Have there been discussions with our US counterparts to see what lessons or expertise can be borrowed? In the current international defence and security climate, many people will be asking an important question: will this affect the UK’s ability to maintain continuous at-sea deterrence? Will it be necessary to adjust the operations timetable of the continuous at-sea deterrent? Finally, can the Defence Secretary confirm the total cost envisaged and that it will have no impact on the rest of the defence programme? If the cost is met by the submarine contingency fund, will that have any impact on the existing submarine programme?

Given that there will be concern about the length of time it has taken to inform the House and the public about this issue, will the Secretary of State tell the House what plans he has to keep Parliament and the country involved and updated throughout this process? Does he agree that public confidence and trust on these issues is crucial, and that people should have been told earlier? There will rightly be anxiety about these matters.

The British public must be assured that everything is being done to resolve them, and they must be confident that Britain’s defence and security is paramount and will be maintained. That is best done through openness and transparency.

I am grateful to the hon. Gentleman, and by and large we agree on the importance of these matters, but I am afraid I must start by saying that I am not particularly minded to take lectures on transparency from someone who was a member of the previous Government. The decisions we have made throughout this process from January 2012 have been carefully balanced. I have, of course, considered throughout whether it would be appropriate, sensible or helpful to make a public statement, and I remind him that the advice we have received throughout from the regulators and experts is that no safety issues are arising, and that this incident scores as a level 0 event on the International Atomic Energy Agency’s scale—an event that requires no action and presents no risk.

We have kept the independent military nuclear safety regulator and the Scottish Environment Protection Agency informed of matters, as is proper, and I have no doubt that there will be people who say that the Scottish Government should have been informed. We will see when we hear from the representative of the Scottish National party in a moment whether it will approach this matter from a responsible and sensible point of view. Key Ministers within the Government were, of course, aware of these issues throughout.

Vernon Coaker asked why we decided to restart the reactor. Once it was clear that there was no safety risk and that a safety case for restarting it had been built and approved by the regulators, we continued with the operation of the test reactor to fulfil its intended purpose: to have delivered the same amount of core burn, and some more, as the most aged operational reactor will have achieved by the end of its service life.

The hon. Gentleman asked about the reactors being built for the Astute submarines, which are also core H reactors. I confirm that after this issue arose, all reactors in-build were re-examined with the best equipment available, to look for signs of anything that might give any further clue as to what has happened with the core H reactor at Dounreay.

The hon. Gentleman also asked about the decision not to have a test reactor for the successor series—the PWR3 reactor. There are several technical reasons for this. The reactor is being built to an entirely different design specification. Because of the way in which technology has evolved, the engineering tolerances will be much less challenging in the PWR3 reactor and we have access to far more advanced computer modelling techniques, which can provide an adequate substitute for prototyping. However, in view of the concerns that have been expressed about this decision, I have asked the chief scientific adviser to review again the evidence on which the decision not to operate a test reactor was based, and to report back to me on the appropriateness of that decision. I will inform the House in due course of the result of that review.

The hon. Gentleman asked whether CASD is affected. It will not be, and that is the point of taking this decision today. Refuelling Vanguard during an existing planned deep-maintenance period means that the operational rotation of the Vanguard-class submarines will not be affected. That is the reason we have taken that decision. It is not a safety-related decision; it is a submarine availability-related decision.

On the question of cost and as I have said already, we expect the total cost of the measures I have announced today to be about £270 million, all of which will come from contingency provision within the submarine programme that is currently unused. We do not expect it to have any impact on the wider defence programme. The contingency within the submarine programme is more than adequate—this amount is substantially less than 10% of the total contingency in the programme.

The hon. Gentleman asked whether I intended to make further statements. Clearly, I will of course notify the House if anything of significance happens; if we make a decision to decommission the reactor at Dounreay early; or if there are any further significant developments in respect of the reactor while it is running. I stress that we have reacted properly throughout, in consultation with the regulatory authorities, and we have dealt with this matter in the same way that any minor incident in a reactor, whether military or civil, would routinely be dealt with.

My right hon. Friend said that the consequences of this announcement for the Astute fleet would be the subject of further review. We all understand that the levels of radioactivity that he has announced are low, but what monitoring will be done of the cooling system in our operational Astutes to reassure the crews and all those involved that they are not in any way at risk?

Can I say to the Secretary of State that the fact that some people may react in an irresponsible way is a reason to be more open on this issue, not a reason to be less open—as he appeared to suggest in his reply to my hon. Friend Vernon Coaker?

I am grateful for the briefings that the Secretary of State has given me and others. It will take three years from the decommissioning of the test reactor to be able to examine fully that hot piece of apparatus. In the meantime, we will continue to build the same reactors for the Astute class of submarine. Is he satisfied that we will do everything we can in that interim period to make certain that we minimise any risk and that we do not elongate or widen the safety margins on the reactor during the manufacturing process or otherwise?

Of course, as the right hon. Gentleman might anticipate, those are questions that I have already asked of the programme managers throughout this process. There are technical factors in the design of the core that limit the scope to change aspects of the design, but now that we are aware that this microscopic breach has occurred in the test reactor, it will focus the examination of the as yet uninstalled cores that are being built for the Astute class of submarine.

The test reactor at Dounreay has been hammered. This is the nuclear equivalent of putting an engine on a test bed and running it flat out at maximum revs to see what happens. It does not mean that what happens to that engine will happen in a car that is being driven normally on the roads.

It will take approximately three years from the time of decommissioning the reactor to being able to examine it fully. We now have to make a decision about whether more will be learned by continuing to run the reactor at Dounreay until its intended decommissioning date in 2015 or by decommissioning it a year and a half early and thus being able to examine the core a year and a half earlier than we otherwise would. The balance needs to be struck on that and I will act on the best scientific advice that I receive.

I commend my right hon. Friend on his decision. What we are seeing is a vindication of the safety models that have been followed by successive Governments in relation to our nuclear submarine programme, and there is certainly no excuse for scaremongering or irresponsible language. In fact, we should be proud and reassured that safety is given such a high priority even at the financial cost that he has outlined.

In order to give the House an understanding of the scale of the problem, will my right hon. Friend give us an indication of the percentage core burn of the Vulcan test reactor, and how that percentage compares with the percentage burn on the Vanguard submarine?

As my right hon. Friend says, Governments of both persuasions over the years have adopted a prudent and precautionary approach to the safety of our nuclear submarine fleet, and have invested money, where it is necessary to do so, on the basis that safety always takes priority. As I have said, the decisions that I am announcing today are not driven by concerns about safety. There is no safety risk identified from this incident. They are driven primarily by concerns about future submarine availability.

The information on core burn is classified, but I can reassure the House that the percentage of core burn on the reactor at Dounreay exceeds by far the percentage of core burn on any of our operational reactors.

Continuous at-sea deterrence is of course the foundation of our deterrent policy. As the Secretary of State knows much better than I do, it requires not only the Vanguard-class submarines to be continuously at sea, but the Trafalgar and the Astute classes to be around. The worst-case scenario would be the refuelling of all Vanguard and Astute submarines. Does he have complete confidence that CASD would be maintained if that were to happen, and what additional capacity would be needed to carry out such an extensive venture?

The hon. Gentleman asks sensible questions, but he is verging into speculative matters at this stage. This is a very tiny flaw in a reactor that has been hammered at maximum output over a long time. It is premature to suggest that when we examine the core we will find some systemic need to refuel all other reactors of a similar type. That is not the expectation.

However, as he would expect, we will plan for every contingency, and the measures that I have announced will allow us to preserve the option of refuelling further Vanguard and Astute submarines should that be deemed expedient in the future.

I thank the Defence Secretary for his statement and commend him on his actions. He has acted, rightly, on the precautionary principle—and, God willing, he is acting more cautiously than is necessary. The UK has the highest nuclear standards, but one can never be too cautious on nuclear safety. If the decision has been taken to refuel Vanguard, which had not been anticipated or expected, and possibly others, what implications will that have, not for the operation of Astute but for the timeline of its production at Barrow?

That is, again, a good question. I am assured that the investment I have announced today to expand capacity at Raynesway, coupled with the buffer already in the supply line—reactors for future Astute class submarines are built ahead of the need to install them in the submarines—means that we can take a core, which was built with the intention of being installed in Astute, to refuel Vanguard. We will have been able to catch up on the production of cores before we get to a point where there would be any impact on the Astute programme. End result: there will be no impact on the timeline of Astute.

The Secretary of State should acknowledge that Scottish MPs and Scotland’s Parliament have voted against nuclear weapons and that there is opposition from the Churches, the Scottish Trades Union Congress and voluntary organisations. He has said that he will plan for every contingency. How will Scottish independence alter his plans, when weapons of mass destruction are removed from Scotland’s environment, and when did he consult Scotland’s Government?

This is from the man whose defence policy is based on being able to join NATO, an avowedly nuclear alliance. As I have said many times in the House, we do not expect the Scottish people to vote for independence and we are not planning for that contingency. However, as one would expect, the Royal Navy operates an extensive set of contingency plans for dealing with all sorts of contingent events that may occur.

My right hon. Friend will be aware that the whole of the deterrent programme, both maintenance and build, is characterised by monopolies that are pretty much unavoidable. Does he agree that, notwithstanding this actually quite small hiccup, this arrangement, under Governments of all kinds, works well and offers lessons for wider consideration across procurement?

Our track record speaks for itself. Since 1963, the Royal Navy has operated 80-odd cores, both at sea and at shore-based test reactors. Rolls-Royce has acted as the technical authority and delivery partner, providing the design and manufacture of cores in an arrangement that has been very satisfactory. Nothing that I am announcing should in any way be taken to undermine the success of that relationship, or Rolls-Royce’s status as a world-leading provider of military reactor cores.

Having worked with radiation for a number of years in my own career and having followed very closely the development of the civil nuclear programme, I fully concur with the Secretary of State’s comments on the underlying science. On level 0 events, similar events, such as moving waste material out of civilian sites, are subject to local communication. Why was there not a parallel situation in the case of Dounreay? Why were local stakeholders not involved? Will he ensure that the chief scientific adviser is given the maximum freedom, within the limits of classified information, to share scientific findings with the broadest possible group of nuclear experts?

The hon. Gentleman can rest assured that within the circle of nuclear experts—it is quite a small circle—there has already been discussion on these issues in the past two years. There is no requirement to notify level 0 events, but we did notify the Scottish Environment Protection Agency and, of course, the military nuclear regulator. It is important to note that SEPA’s primary focus is on emissions from the site—that is, what is in the discharge from the site—and there has been no measurable change in the radiation discharge. That is the important point for people living in those communities.[This section has been corrected on 11 March 2014, column 3MC — read correction]

If the defect seen on the Vulcan test reactor at Dounreay were to be identified in one of the Astute or Vanguard-class submarines, what would the consequences be, from a safety perspective, for the crew on board those vessels? How would the removal of one or more submarine affect operational maritime capabilities?

My hon. Friend asks a good question. I emphasise again that there are no safety implications from this type of event—a submarine could continue to operate safely. This is a tiny amount of radiation in a coolant that is itself circulating in a closed system inside the sealed reactor shield, so there is no risk to the submarine crew. If such an event occurred, it would be detected almost immediately because of the daily sampling and analysis of coolant water. We are already looking at the operational implications, in a reactor of this type, of a very minor breach. As I have already told the House, the test reactor at Dounreay was restarted in 2012 and has subsequently run without any further problems. It is not absolutely clear that the result of such a minor event occurring in an operational reactor would necessarily mean that the reactor would have to be withdrawn from service. Clearly, we would do so on a precautionary basis while we considered a longer term course of action, but it is not yet clear that that would have to be the long-term state of affairs.

The Secretary of State has said a number of times that SEPA was kept informed. Will he inform the House at what stage it was first informed? Given that SEPA is an Executive agency of the devolved Scottish

Government, were Scottish Ministers informed by SEPA and, if that was the case, why were Scottish Ministers informed but Members of this House not?

SEPA was informed in October 2012 and has been involved in the discussions since that point. SEPA is an Executive agency of the Scottish Government, but it deals with operators in relation to the discharge of its regulatory functions on a properly regulated statutory basis and, usually, on a confidential basis. Clearly, SEPA did not feel that this event, as a level 0 event, needed to be brought to the attention of Ministers or anyone in the central Scottish Government.

I thank my right hon. Friend for confirming that no lives were ever endangered by this activity. What discussions has he had with Babcock to ensure that it has the skilled work force in place and is able to deliver the work? It is important to ensure that that happens.

Obviously, the implications for Devonport are that a line of work, which was expected to end with the completion of the current refuelling of Vengeance, will now continue at least until 2019, with the refuelling of HMS Vanguard. At this stage, we have not quantified the precise impact on jobs and other activities at Devonport, but it is likely to be modest. Most of the people employed on the refuelling programme were expected to be absorbed elsewhere in the dockyard work force. We are confident that, with the announcements I have made today, there will be the capacity to carry out the Vanguard refuelling and to retain the ability to carry out the Victorious refuelling if necessary.

The stupidity of both the United Kingdom Government and the Scottish Government knows no bounds. It is clear from the fact that the Scottish Government have known about this for nearly two years and the United Kingdom Government have known about it for more than two years that they hold the people of this country in contempt. I live very close to Faslane, and it worries me that something could happen that the people of my country and my city know nothing about. The Secretary of State must go and tell people about it, otherwise no one will believe anything he says in future about anything to do with nuclear power.

I am not sure about taking any lessons on stupidity. I am afraid that this is scaremongering of the worst kind. I have told the hon. Gentleman and the House that no safety issues are at stake, and all the scientific evidence supports the position that I have taken. Level 0 events are not routinely made public; they are not routinely reported. That has been the practice of successive Governments, and it is the practice throughout the civil and military nuclear sector.

The refit for HMS Vanguard will take three and a half years, and that was planned. Does not that fact, and the requirement for us to have a permanent at-sea deterrent, support the plans for a fleet of four Successor SSBNs?

Indeed they do. If we are to maintain our posture of continuous at-sea deterrence, we will need to begin replacing the current fleet in the late 2020s. That is not primarily to do with the lives of the reactors or the cores; it is to do with the life expectancy of other components of the submarines that cannot effectively be replaced. The final decision to replace the Vanguard-class submarines with Successors will be made in 2016.